Corrosion resistant structural foam

ABSTRACT

Titanates and zirconates bearing organic substituents can act as corrosion inhibitors when added to foamable compositions based on thermosettable synthetic resins such as epoxy resins. Combinations of organometallates containing certain specific types of substituents provide synergistic improvements in the properties of structural reinforcement foams obtained by heating and curing the foamable compositions.

This application claims priority from provisional application Serial No.60/098,110, filed Aug. 27, 1998, and is a divisional of Ser. No.09/313,592, filed May 18, 1999, now U.S. Pat. No. 6,103,784.

BACKGROUND OF THE INVENTION

1. Field of The Invention

The invention relates to a foam that resists corrosion and that isuseful for reinforcing structural members and the like.

2. Discussion of the Related Art

It is known that a number of industries, e.g., the automobile industry,require parts that are both strong and light-weight. One attempt toachieve this balance between strength and minimal weight provides forhollow metal parts. However, hollow metal parts are easily distorted.Accordingly, it is also known that the presence of structural foam inthe cavities of the hollow parts can improve strength and stiffness ofsuch parts.

Generally, such foams comprise a thermosettable resin such as an epoxyresin, a blowing agent and a filler such as hollow glass microspheres.Preferably, these foams have a density of about 20-40 lb/ft³ (about0.30-0.65 g/cc) and are able to withstand heat in excess of 175° C.,most preferably in excess of 200° C. Optional ingredients indudecuratives, processing aids, stabilizers, colorants, and UV absorbers.

Specific formulas for structural foam can vary widely. For example, U.S.Pat. No. 5,575,526 teaches several structural foams based on polyesterand epoxy resins. U.S. Pat. No. 5,755,486 disdoses thermally expandableresin-based materials containing, for example, epoxy resin,acrylonitrile-butadiene rubber, calcium carbonate, carbon black, fumedsilica, glass spheres, curing agent, accelerator, and blowing agent.Structural reinforcement foams such as, e.g., TEROCORE® (a product ofHenkel Surface Technologies) are now used in a variety of industries.

One characteristic of structural reinforcement foams is that they startas expandable resins that form gas pockets (cells) when cured. Whenexposed to ordinary environmental conditions, these cells can trap saltand water. Salt and water corrode the metal parts, which are commonly incontact with the foam, and the resulting metal oxide degrades theability of the foam to adhere to the metal. Eventually, the foam isforced from the metal part, thereby weakening the part.

SUMMARY OF THE INVENTION

Surprisingly, the inventors have found that organometallate compoundsselected from the group consisting of organic titanates and organiczirconates can act as corrosion inhibitors when added to structuralreinforcement foam formulations. That is, the organometallate compoundsreduce the amount of corrosion which takes place on a metal surface(particularly a ferrous metal surface such as steel) in contact with areinforcing foam.

The foamable compositions comprise, in addition to acorrosion-inhibiting amount of one or more organometallate compounds,one or more thermosettable synthetic resins, one or more curatives, andone or more blowing agents. In one especially advantageous aspect of theinvention, the foamable composition is in the form of a pliable doughwhich additionally contains one or more fillers, particularly hollowglass microspheres.

Synergistic improvements in certain properties can be achieved throughthe use of a combination of different types of organometallatecompounds.

DETAILED DESCRIPTION OF THE INVENTION

Organic titanates and zirconates suitable for use as corrosioninhibitors in the present invention are well known in the art and aredescribed, for example, in the following U.S. Pat. Nos. (each of whichis incorporated herein by reference in its entirety): 2,984,641;4,069,192; 4,080,353; 4,087,402; 4,094,853; 4,096,110; 4,098,758;4,122,062; 4,192,792; 4,261,913; 4,423,180; 4,450,221; 4,512,928;4,600,789; 4,623,738; 4,634,785; 4,659,848; 4,788,235; 4,792,580;5,045,575; and 5,707,571. A number of suitable titanates and zirconatesare available from commercial sources, such as Ajinomoto Company, Inc.,of Japan under the PLENACT trademark and Kenrich Petrochemicals ofBayonne, N.J. under the KEN-REACT trademark, including NZ-37 (aparticularly preferred zirconate), NZ-38, LICA 38, LICA 97, KZTPP, CAPROL 38/H, KR-238M (a particularly preferred titanate which is anamino(meth)acrylate adduct of a tetrasubstituted pyrophosphato titanate;the chemical structure of KR-238M is shown in U.S. Pat. No. 5,340,946,the disclosure of which is incorporated herein by reference in itsentirety), KR-55 (a particularly preferred titanate which is a phosphiteadduct of a neoalkoxy-substituted titanate; the chemical structure ofKR-55 is shown in U.S. Pat. No. 5,045,575, the disclosure of which isincorporated herein by reference in its entirety), KZ-55, KR-41B,KR-46B, KR-TTS, KR-201, KR-33BS, KR-133BS, KR-39BS, KR-139BS, KR-34S,KR-34BS, KR-134S, KR-134BS, KR-44, KR-52S, KR-63S, KR-66S, KR-27S,KR-9S, KR-12, KR-112S, KR-212, KR-38S, KR-138S, KR-2388, KR-58FS,KR-158FS, KR-62ES, KR-262ES, KR-36C, KR-41B, NZ-44, LZ-38 and KR-46B.

Suitable organometallates are characterized in general by having foursubstituents covalently bonded to titanium or zirconium atoms (i.e., theorganometallates are tetrasubstituted) with the four atoms directlybonded to the metal atom being oxygen atoms. As will be discussed inmore detail hereinafter, the metal atoms may optionally be complexed byvarious types of moieties to form adducts.

It is particularly preferred to use one or more titanates and/orzirconates containing at least one neoalkoxy substituent attached totitanium or zirconium such as those described, for example, in U.S. Pat.Nos. 4,600,789; 4,623,738 and 5,045,575.

The neoalkoxy substituent(s) preferably correspond to the generalstructure

wherein R, R¹ and R² may be the same or different and are each amonovalent alkyl, alkenyl, alkynyl, aralkyl, aryl, or alkaryl grouphaving up to 20 carbon atoms or a halogen or ether substitutedderivative thereof. R² may also be an oxy derivative or an ethersubstituted oxy derivative of the aforementioned groups. (e.g., C₁₋-C₃alkoxy, phenoxy). In one embodiment, R² is C₁-C₆ alkyl and R¹ and R² areallyloxymethyl (—CH₂—O—CH₂—CH═CH₂). The titanate or zirconate may alsobe an adduct of a phosphite or other phosphorus-containing moiety. Suchmoeities may be regarded as complexing or chelating agents, whereincertain functional groups in the entity are associated with the metalatom (Ti or Zr) in the titanate or zirconate. The entity may preferablybe a mono or di-substituted hydrogen phosphite. Suitable adducts of thistype are described, for example, in U.S. Pat. Nos. 4,080,353; 4,261,913;4,512,928; 4,659,848; 4,788,235; 4,792,580 and 5,045,575.

Another particularly preferred class of organometallate compoundincludes amine adducts of titanates and zirconates. The metal atom ispreferably substituted with at least one phosphorus-containingsubstituent selected from the group consisting of phosphite, phosphateand pyrophosphate. In a particularly desirable embodiment, the amineportion of the adduct contains an unsaturated carboxylate functionalitysuch as (meth)acrylate. The commercial product KEN-REACT KR-238Mtitanate (available from Kenrich Petrochemical) is an example of thistype of titanate adduct. Amine adducts of titanates and zirconates arealso described in U.S. Pat. Nos. 4,512,928 and 5,340,946.

Sufficient organometallate compound is incorporated into the foamablecomposition so as to reduce the extent of corrosion which occurs whenthe structural reinforcement foam formed from the foamable compositionis placed in contact with the surface of a metal part. The optimumamount of organometallate compound will vary somewhat depending upon theidentity of the organometallate compound(s) selected for use and thetype of metal surface, among other factors, but may be readilydetermined by routine experimentation. Total amounts of organometallatecompounds in the range of from about 0.1 to about 2 weight of % based onthe total weight of the foamable composition will generally beeffective, however.

In one embodiment of the invention, at least two differentorganometallate compounds are utilized. Even more preferably, at leastthree different organometallate compounds are utilized. The differentorganometallate compounds are desirably selected from at least two, morepreferably three, of the following classes of materials: (a) titanatescontaining at least one neoalkoxy substituent bonded to titanium and/orat least one phosphite moiety in the form of an adduct, (b) zirconatescontaining at least one neoalkoxy substituent bonded to zirconium and/orat least one substituted or unsubstituted benzoate group bonded tozirconium, and (c) titanates containing at least one pyrophosphatesubstituent bonded to titanium and/or at least one amine moiety in theform of an adduct.

A preferred foamable formulation comprises about 0.1 to about 1 weight %(more preferably 0.3 to 0.5 weight %) Uitanates of type (a), about 0.1to about 1 weight % (more preferably 0.1 to 0.2 wt %) zirconates of type(b) and about 0.1 to about 0.5 weight % (more preferably, 0.2 to 0.3weight %) titanates of type (c).

In addition to the organometallate compounds which act as corrosioninhibitors, preferred foam formulations contain about 35 weight percentto about 85 weight percent of one or more thermosettable syntheticresins, about 10 weight percent to about 60 weight percent of one ormore fillers (with hollow glass microspheres being especiallypreferred), about 0.1 weight percent to about 5 weight percent of one ormore blowing agents, and about 0.1 weight percent to about 15 weightpercent of one or more curatives. The foamable composition may alsocontain effective amounts of other additives such as blowing agentactivators, silanes, toughening/flexibilizing agents,thixotropic/rheological control agents, colorants, and stabilizers. Itis particularly advantageous to select formulation components which,when mixed together, provide a foamable dough of putty-like consistencywhich can be readily molded or shaped into any desirable configurationprior to foaming and curing.

While in principle any of the thermosettable synthetic resins known inthe art may be employed, including, for example, vinyl esters, thermosetpolyesters, urethanes, phenolic resins, and the like, the presentinvention is especially well-suited for use with epoxy resin-basedsystems.

Any of the thermosettable resins having an average of more than one(preferably about two or more) epoxy groups per molecule known orreferred to in the art may be utilized as the epoxy resin component ofthe present invention.

Epoxy resins are described, for example, in the chapter entitled “EpoxyResins” in the Second Edition of the Encyclopedia of Polymer Science andEngineering, Volume 6, pp. 322-382 (1986). Exemplary epoxy resinsinclude polyglycidyl ethers obtained by reacting polyhydric phenols suchas bisphenol A, bisphenol F, bisphenol AD, catechol, resorcinol, orpolyhydric alcohols such as glycerin and polyethylene glycol withhaloepoxides such as epichlorohydrin; glycidylether esters obtained byreacting hydroxycarboxylic acids such as p-hydroxybenzoic acid orbeta-hydroxy naphthoic acid with epichlorohydrin or the like;polyglycidyl esters obtained by reacting polycarboxylic acids such asphthalic acid, tetrahydrophthalic acid or terephthalic add withepichlorohydrin or the like; epoxidated phenolic-novolac resins(sometimes also referred to as polyglycidyl ethers of phenolic novolaccompounds); epoxidated polyolefins; glycidylated aminoalcohol compoundsand aminophenol compounds, hydantoin diepoxides and urethane-modifiedepoxy resins. Mixtures of epoxy resins may be used if so desired; forexample, mixtures of liquid (at room temperature), semi-solid, and/orsolid epoxy resins can be employed. Any of the epoxy resins availablefrom commerical sources are suitable for use in the present invention.Preferably, the epoxy resin has an epoxide equivalent molecular weightof from about 150 to 1000. The use of epoxy resins based on glycidylethers of bisphenol A is especially advantageous. The epoxy resinpreferably contains an average of about 2 epoxy groups per molecule andshould be selected so as to provide the desired combination ofproperties in both the foamable dough and the final cured foam.

The hardening of the thermosettable synthetic resins utilized in thepresent invention may be accomplished by the addition of any of thechemical materials known in the art for curing such resins. Suchmaterials are referred to herein as “curatives”, but also include thesubstances known to workers in the field as curing agents, hardeners,activators, catalysts or accelerators. While certain curatives promotecuring by catalytic action, others participate directly in the reactionof the resin and are incorporated into the thermoset polymeric networkformed by condensation, chain-extension and/or crosslinking of thesynthetic resin. Where the thermosettable synthetic resin is an epoxyresin, it is particularly desirable to employ at least one curativewhich is a nitrogen-containing compound. Such curatives (along withother curatives useful for hardening epoxy resins) are described in thechapter in the Encyclopedia of Polymer Science and Engineeringreferenced hereinabove. Suitable nitrogen-containing compounds useful ascuratives include amino compounds, amine salts, and quatemary ammoniumcompounds. Particularly preferred types of nitrogen-containing compoundsinclude amine-epoxy adducts, imidazoles, ureas, and guanidines. In onedesirable embodiment of the invention, two or more different types ofthese nitrogen-containing compounds are used in combination.

Amine-epoxy adducts are well-known in the art and are described, forexample, in U.S. Pat. No.s 3,756,984; 4,066,625; 4,268,656; 4,360,649;4, 542,202; 4,546,155; 5,134,239; 5,407,978; 5,543,486; 5,548,058;5,430,112; 5,464,910; 5,439,977; 5,717,011; 5,733,954; 5,789,498;5,798,399 and 5,801,218, each of which is incorporated herein byreference in its entirety. Such amine-apoxy adducts are the products ofthe reaction between one or more amine compounds and one or more epoxycompounds. Carboxylic acid anhydrides, carboxylic acids, phenolicnovolac resins, water, metal salts and the like may also be utilized asadditional reactants in the preparation of the amine-epoxy adduct or tofurther modify the adduct once the amine and epoxy have been reacted.Preferably, the adduct is a solid which is insoluble in the epoxy resincomponent of the present invention at room temperature, but whichbecomes soluble and functions as an accelerator to increase the curerate upon heating. While any type of amine could be used (withheterocyclic amines and/or amines containing at least one secondarynitrogen atom being preferred), imidazole compounds are particularlypreferred. Illustrative imidazoles include 2-methyl imidazole,2,4-dimethyl imidazole, 2-ethyl-4-methyl imidazole, 2-phenyl imidazoleand the like. Other suitable amines include, but are not limited to,piperazines, piperidines, pyrazoles, purines, and triazoles. Any kind ofepoxy compound can be employed as the other starting material for theadduct, including monofunctional, bifunctional, and polyfunctional epoxycompounds such as those described previously with regard to the epoxyresin component. Suitable amine-epoxy adducts are available fromcommercial sources such as Ajinomoto, Inc., Shell, Pacific AnchorChemical Company, and the Asahi Chemical Industry Company Limited. Theproducts sold by Ajinomoto under the trademarks AJICURE PN-40 andAJICURE PN-23 are especially preferred for use in the present invention.

Dicyandiamide (sold commercially by Air Products under the trademarkDICY) is also a particularly preferred curative, although otherguanidine compounds may also be utilized. The curative system may alsocomprise one or more ureas, either alone or in combination with othertypes of curatives (especially guanidines such as dicyandiamide).Suitable ureas include alkyl and aryl substituted ureas. Many such ureasare available commercially, for example, N,N′-dimethyl urea, which issold under the trademark AMICURE UR by Air Products. Imidazoles,including alkyl and aryl substituted imidazoles such as 2-ethyl-4-methylimidazole, constitute another class of suitable curatives.

In one desirable embodiment of the invention, dicyandiamide (preferably,about 0.5-8 wt % based on the total weight of the foamable composition)is used in combination with an amine-epoxy adduct (preferably, about0.1-5 wt %) in the curative system.

The curative system (i.e., the specific curatives and the amounts ofsuch curatives) should be selected such that it does not catalyze curingof the foamable composition to any significant extent under typicalstorage conditions over an extended period of time. Preferably, thecomponents of the curative system are adjusted such that the foamablecomposition retains a workable consistency (in one embodiment of theinvention, a consistency resembling that of a pliable dough or putty)for more than two weeks at 130° F.) and does not expand in volume ordecrease in specific gravity under such conditions to an unacceptableextent, yet foams and cures within 10 minutes upon being heated at 150°C. or higher with no appreciable deterioration in performance duringstorage.

Selection of the blowing agent or blowing agents to be used in thepresent invention is not believed to be particularly critical, althoughchemical blowing agents rather than physical blowing agents arepreferred if a storage-stable, ready-to-use one part composition isdesired. Any of the chemical blowing agents known in the art may beemployed, with azodicarbonamide (also sometimes referred to as1,1′-azobisformamide, AZDC or ADC) and sulfonyl hydrazides providingparticularly good performance. In one embodiment of the invention,azodicarbonamide is utilized as the predominate or, more preferably,sole blowing agent; mixtures with sulfonylhydrazides may be desirablefor certain purposes, however. Azodicarbonamide is available from anumber of commercial sources; for example, it is sold under thetrademark UNICELL by Doug Jin Chemical of South Korea and under theCALOGEN trademark by Uniroyal Chemical. “Activated” or “modified” formsof azodicarbonamide may be used to advantage. Suitable sulfonylhydrazideblowing agents include, but are not limited to,p,p′-oxybis(benzenesulfonylhydrazide) (sold by Uniroyal Chemical underthe trademark CELOGEN OT), p-toluenesulfonylhydrazide (sold by UniroyalChemical under the trademark CELOGEN TSH) and the like. The particlesize of the blowing agent may be adjusted so as to provide the desiredfoaming characteristics in the cured foam. Smaller particle sizes, forexample, tend to provide foams having more uniform cell structure.

In some formulations, it may be desirable to also use a blowing agentactivator or accelerator so as to lower the temperature at which releaseof gas from the blowing agent takes place. Suitable blowing agentactivators include, but are not limited to, ureas (such as thesurface-coated, oil-treated urea sold by Uniroyal Chemicals under thetrademark BIKOT) polyols, organic acids, amines, and lead, zinc, tin,calcium and cadmium oxides and salts (including carboxylic acid salts).Typically, from about 0.1% to about 2% blowing agent activator based onthe weight of the foamable composition is employed, although the optimumamount will of course vary depending upon the activator/acceleratorselected, the amount of blowing agent, cure temperature and othervariables. Excess activator should not be used since the storagestability may thereby be adversely affected.

It will be especially desirable to include one or more glass fillers inthe foamable composition, as such fillers impart useful characteristicsto the resulting structural reinforcement foam. For example, hollowglass microspheres may be added to reduce the density of the foam whilemaintaining good strength and stiffness. Commercially available hollowglass microspheres (sometimes also referred to as glass microballoons ormicrobubbles) include the materials sold by Minnesota Mining &Manufacturing under the trademark SCOTCHLITE, with suitable gradesincluding those available under the designations B38, C15, K20, and VS5500. The glass microspheres preferably have diameters in the range offrom about 5 to 200 micrometers (preferably, no greater than 70micrometers). The crush strength of the hollow glass microspheres may beselected in accordance with the desired characteristics of the curedthermoset foam or reinforced structural member containing such foam. Ina particularly desirable embodiment of the invention, hollow glassmicrospheres comprise from about 5 to about 50 percent by weight of thefoamable composition. Glass fiber is another preferred type of glassfiller, since it helps increase the strength and stiffness of thestandard reinforcement foam. The glass fiber may be chopped, milled, orin other suitable physical form.

Other types of fillers may also optionally be present in the foamablecomposition. Any of the conventional organic or inorganic fillers knownin the thermosettable resin art may be used including, for example,silica (including fumed or pyrogenic silica, which may also function asa thixotropic or rheological control agent), calcium carbonate(including coated and/or precipitated calcium carbonate, which may alsoact as a thixotropic or rheological control agent, especially when it isin the form of fine particles), fibers other than glass fibers (e.g.,wollastonite fibers, carbon fibers, ceramic fibers, aramid fibers),alumina, clays, sand, metals (e.g. aluminum powder), microspheres otherthan glass microspheres such as ceramic microspheres, thermoplasticresin microspheres, thermoset resin microspheres, and carbonmicrospheres (all of which may be solid or hollow, expanded orexpandable) and the like.

Other optional components include diluents (reactive or non-reactive)such as glycidyl ethers, glycidyl esters, acrylics, solvents andplasticizers, toughening or flexibilizing agents (e.g., aliphaticdiepoxides, polyaminoamides, liquid polysulfide polymers, rubbersincluding liquid nitrile rubbers such as butadiene-acrylonitilecopolymers, which may be functionalized with carboxy groups, aminegroups or the like), coupling agents/wetting agents/adhesion promoters(e.g., silanes), colorants (e.g., dyes and pigments such as carbonblack), stabilizers (e.g., antioxidants, UV stabilizers) and the like.

Methods of preparing structural foam are well-known in the industry. Toobtain the corrosive resistant foams of the present invention, simplyadd the organometallate compounds at any point of the known processes.

For a preferred method of making a one-part epoxy resin structural foam,an epoxy resin, a rubber, the organometallate compound(s), and anoptional silane are admixed to form Mixture 1. Then, glass microspheresand/or glass fiber, blowing agent, fumed silica, calcium carbonate,colorant, curative(s) and urea (accelerator for blowing agent) areadmixed to Mixture 1. More preferably, the glass microspheres/fiber andthe blowing agent are admixed together to form Mixture 2. Then, Mixture2 and Mixture 1 are admixed together before admixing the remainingingredients.

Alternatively, resin and the organometallate compound(s) are admixedfirst, followed by blowing agent, glass microspheres and glass fibers.Thereafter, rubber, curing agent, accelerator, urea and fumed silica areadded. For one improvement, resin and organometallate compound(s) areadmixed first, followed by blowing agent and glass microspheres.Thereafter, rubber, curative(s), urea, fumed silica and glass fibers areadded. Adding the glass fiber last produced better results for someapplications of the structural foam.

Once all of the ingredients are together, the dough is vacuumed toremove air. The preferred finished product has the consistency of doughfor easier handling. The dough may be shaped by extrusion or by hand orother means into any desired configuration. A quantity of the dough can,for example, be placed into the appropriate cavity of a metal part Thefoamable composition is foamed and cured by heating, preferably to atleast about 250° F. (about 120° C.), more preferably at least about 300°F. (about 150° C.).

The foamable compositions of the present invention may be utilized inany end-use application where a relatively light-weight, yet strong,thermoset foam is needed. However, the foamable compositions areespecially useful in the production of automobiles and other vehicles tomaintain or increase the strength of structural members such as rockers,pillars, radiator support beams, doors, reinforcing beams and the like.The use of structural foams in such applications is described, forexample, in U.S. Pat. Nos. 4,901,500; 4,908,930; 4,751,249, 4,978,562;4,995,545; 5,124,186; 5,575,526; 5,755,486; 4,923,902; 4,922,596;4,861,097; 4,732,806; 4,695,343; and 4,610,836 (each of which isincorporated herein by reference in its entirety).

EXAMPLES Example 1-3

The components listed in Table 1 were combined to provide a foamablecomposition in accordance with the present invention. Lap shear wastested under SAEJ1523 standards using 1 mm thick samples.

In Example 1, the resulting dough was tested under European testingconditions (PDA test and Volkswagen test) to determine adhesion tometal. A 1″×1″×0.040″ sample of Example 1 was placed between each ofeight sets of 0.06″×1″×4″ samples of cold-rolled steel (CRS) and fivesets of 0.04″×1″×4″ samples of hot-dipped galvanized steel (HDG). Forthe CRS samples, three sets were cured in the presence of metal spacerswhile five sets were cured in the presence of paper clips. Each samplewas heated at 350° F. (177° C.).

Example 2 was tested using the method described above, but under GeneralMotors 9505 Cycle G @ 30 cycles. The control samples (foamablecompositions having compositions analogous to those of Examples 1-3, butwhich did not contain any organometallate compounds) had initial lapshear of between about 900-1000 psi. However, the control samples fellapart after the General Motors cycling test so that post-cycle lap sheardata could not be obtained. Therefore, it was surprising that any datacould be measured at all for the test samples prepared using thefoamable compositions of the present invention. Accordingly, apost-cycle lap shear of 850 psi is a vast improvement over the controlsamples.

Example 3 was identical in composition to Example 2 and was also testedusing the aforedescribed General Motors cycling test.

Examples 4-10

The components listed in Table 2 were combined to provide foamablecompositions. Examples 5-8 and 10 illustrate the present inventionwherein one or more organometallate compounds were employed, whereasExamples 4 and 9 are comparative examples prepared in the absence of anyorganometallate compound. In these examples, lap shear was measured on⅛^(th) inch thickness samples before cycling. The 3 point bendmeasurement refers to a test for flexural strength wherein a sample isplaced between two supports and an opposing pressure is exerted on apoint between the two supports.

The data shown in Table 2 demonstrate that improvements in the flexuralstrength and lap shear of the structured reinforcement foam are obtainedwhen at least one titanate, zirconate, or silane is present. However, asynergistic improvement was achieved in Example 8 when an organiczirconate and two different types of organic titanates were present atthe same time. Example 8 exhibited the second highest flexural strengthand the highest lap shear of all the samples tested in this series.

Although Example 5 contained about twice the amount of each of the samethree organometallates as in Example 8, Example 8 exhibited betterflexural strength and lap shear than Example 5. At the same time,however, Example 5 had better flexural strength and lap shear than thecontrol Example 4. Thus, the comparison between Example 5 and 8indicates that increasing the amounts of the organometallate compoundsdoes not necessarily provide further improvements in physicalproperties. Therefore, foam properties may be optimized at someintermediate organometallate concentration, which may be readilydetermined for any particular type of foamable composition by routineexperimentation.

While the addition of silane in Example 9 improved both lap shear andflexural strength as compared to control Example 4, the standardreinforcement foam produced in Example 9 bent the substrate (metalpanel) to which it was adhered as the foam shrunk. The same phenomenonwas also observed in Example 10, which used a single organometallatecompound.

One must note that any improvement in the initial lap shear or the 3point bend results achieved by the addition of one or moreorganometallate compounds is a bonus. The primary advantage of usingsuch compounds is an improvement in the post-cycling lap shear results,which correlates with increased corrosion resistance.

Examples 11-19

The components listed in Table 3 were combined to provide foamablecompositions in accordance with the present invention wherein theamounts of the blowing agent and nitrile rubber(flexibilizing/toughening agent) were varied. Each of the examples alsocontained the following components: 1.3 wt % CAB-O-SIL TS-720 silica,0.6 wt % AJICURE PN-23 amine-epoxy adduct curative, 0.4 wt % BIK OT ureablowing agent accelerator, 0.5 wt % KEN-REACT KR-55 organic titanate,0.2 wt % KEN-REACT NZ-37 organic zirconate, and 0.2 wt % KEN-REACT 238Morganic titanate.

The data obtained for these examples show that significant changes inlap shear and flexural strength do not take place when the blowing agentand toughening/flexibilizing agent contents are varied within the rangestested. Example 19 was used as a “control” or reference sample forpurposes of this comparison. The amounts of blowing agent andtoughening/flexibilizing agent used in Example 12 provided an optimumflexural strength balanced by a minimal decrease in lap shear.

Examples 20-28

The series of foamable compositions in Table 4 was prepared and testedusing the procedures set forth in Examples 4-10 to determine the effectsof using a finer grade of dicyandiamide curative (DICY CG325) andvarying the levels of silica, glass fiber and glass microspheres. Eachcomposition contained 0.4 wt % BIK OT urea blowing agent accelerator,0.5 wt % KEN-REACT KR-55 organic titanate (except for Example 24, whichcontained 0.4 wt % KEN-REACT KR-55), 0.2 wt % KEN-REACT NZ37 organiczirconate, and 0.2 wt % KEN-REACT KR238M organic titanate, in additionto the components listed in Table 4. The structural reinforcement foamobtained in Example 24 possessed particularly good physical propertiesas compared to the “control” (Example 28).

Examples 29-33

The series of foamable compositions in Table 5 was prepared and testedusing the procedures set forth in Examples 4-10 to determine the effectof varying the amount of fumed silica in the formulation. Eachcomposition contained 0.5 wt % AJICURE PN-23 amine-epoxy adductcurative, 0.2 wt % CELOGEN AZ-120 blowing agent, 0.4 wt % KEN-REACTKR-55 organic titanate, 0.2 wt % KEN-REACT NZ37 organic zirconate and0.2 wt % KEN-REACT KR238M organic titanate, in addition to thecomponents listed in Table 5. Example 31 exhibited the best flexuralstrength and lap shear as compared to the “control” (Example 29).

Example 34-38

The examples set forth in Table 6 demonstrate that the order in whichthe components of the foamable composition are combined can improve foamproperties for certain applications. For Examples 34 and 36, the epoxyresins and organometallate compounds were mixed together first. Next,blowing agent, glass microspheres and glass fibers were admixed to theepoxy resin/organometallate compound mixture. Rubber, curatives, ureaand fumed silica were added last to the mixture. Examples 35 and 37varied from Examples 34 and 36 in that the glass fiber was added withthe lastly added components instead of with the second group ofcomponents. Adding the glass fiber last produced structuralreinforcement foams having improved flexural strength, as measured bythe 3 point bend test.

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Wt. Wt. Wt. Component Identity Supplier % % %Epoxy Resins PEP 6134 Peninsula 36.4 36.94 36.94 Polymers ARALDITE Ciba19.6 19.89 19.89 6060 Curatives Dicyandiamide DICY 200X Air Products4.24 — — DICY CGNA Air Products — 4.3 4.3 Amine-Epoxy AJICURE Ajinomoto1.07 1.09 1.09 Adduct PN-23 Blowing Agents Sulfonyl CELOGEN OT Uniroyal0.97 0.99 0.99 Hydrazide Diaza- CELOGEN Uniroyal 0.97 0.99 0.99carbonamide AZ120 Urea Blowing Agent BYK OT Uniroyal 0.56 0.57 0.57Activator Organometallates Titanates KEN-REACT Kenrich 0.10 0.1 0.1KR-55 Petrochemicals KEN-REACT Kenrich 0.19 0.2 0.2 238M PetrochemicalsZirconate KEN-REACT Kenrich 0.10 0.1 0.1 NZ-37 Petrochemicals FillersCalcium ULTRA Pfizer 4.68 4.75 4.75 Carbonate PFLEX Silica CAB-O-SILCabot 3.46 3.51 3.51 TS-720 Glass B-38/V5 5500 3M 21.84 22.16 22.16Microspheres Aluminum Reynolds 1.46 — — Powder Colorants Carbon BlackMONARCH Cabot 0.13 0.13 0.13 120 Pthalocyanine 626 Blue 0.01 — —Toughening/ Nipol 1312 Zeon 4.22 4.28 4.28 Flexibilizing AgentProperties Uncured Specific 0.79 — 0.79 Gravity Cured Specific 0.48 —0.46 Gravity % Expansion 65 — 71 Initial Shear, psi 936 975 943 CycledShear, psi — 850 —

TABLE 2 Ex. 4* Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9* Ex. 10 Component IdentitySupplier Wt. % Wt. % Wt. % Wt. % Wt. % Wt. % Wt. % Epoxy Resin DER 331Dow Chemical 45 44.0 44.5 44.5 44.5 44.5 44.5 Curatives DicyandiamideDICY CGNA Air Products 3.7 3.7 3.7 3.7 3.7 3.7 3.7 Amine-Epoxy AdductAJICURE PN-23 Ajinomoto 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Blowing AgentsDiazacarbonamide CELOGEN AZ120 Uniroyal 1.2 1.2 1.2 1.2 1.2 1.2 1.2 UreaBlowing Agent BIK OT Uniroyal 0.4 0.4 0.4 0.4 0.4 0.4 0.4 ActivatorOrganometallate Titanates KEN-REACT KR-55 Kenrich Petrochemicals — 0.90.9 — 0.5 — — KEN-REACT 238M Kenrich Petrochemicals — 0.5 — 0.46 0.2 —KEN-REACT LICA-38 Kenrich Petrochemicals — — — — — — 0.9 ZirconateKEN-REACT NZ-37 Kenrich Petrochemicals — 0.5 — 0.46 0.2 — — Silane D6020Dow Chemical — — — — — 0.9 — Fillers Silica CAB-O-SIL TS-720 Cabot 1.31.3 1.3 1.3 1.3 1.3 1.3 Glass Fiber   —   — 9.4 9.2 9.3 9.3 9.3 9.3 9.3Glass Micropheres B-38/V5 5500 3M 32.8 32.2 32.5 32.5 32.5 32.5 32.5Toughening/Flexibilizing Nipol 1312 Zeon 5.6 5.6 5.6 5.6 5.6 5.6 5.6Agent Nitrile Rubber Properties Lap Shear, psi 136 214 146 174 267 152173 3 Point Bend, psi 42.7 48.7 49.7 48.3 55 56.7 54.7 *Comparativeexample

TABLE 3 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex. 19Component Identity Supplier Wt. % Wt. % Wt. % Wt. % Wt. % Wt. % Wt. %Wt. % Wt. % Epoxy Resins PEP 6134 Peninsula 22.7 22.5 22.1 21.9 22.422.3 22.2 22.2 22.2 Polymers DER 331 Dow Chemical 22.7 22.5 22.1 21.922.4 22.3 22.2 22.2 22.2 Additional Curative DICY CGNA Air Products 3.83.7 3.7 3.6 3.7 3.7 3.7 3.7 3.7 Dicyandiamide Blowing Agent CELOGENAZ-120 Uniroyal 1.2 1.2 1.2 1.2 0.7 0.9 1.4 1.6 1.3 DiazacarbonamideAdditional Fillers Glass Fiber   —   — 9.5 9.4 9.2 9.1 9.3 9.3 9.3 9.29.2 Glass Microspheres B-38/V5 5500 3M 33.1 32.8 32.2 31.9 32.7 32.632.4 32.4 32.4 Toughening/Flexibilizing NIPOL 1312 Zeon 3.8 4.7 6.4 7.35.6 5.6 5.6 5.5 5.5 Agent Properties Lap Shear, psi 167 162 157 178 180190 175 low 180 3 Point Bend, psi 27 31 20 26 29 29 26 28 29

TABLE 4 Ex. 20 Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Ex. 27 Ex. 28Component Identity Supplier Wt. % Wt. % Wt. % Wt. % Wt. % Wt. % Wt. %Wt. % Wt. % Epoxy Resins PEP 6134 Peninsula 22.5 23 23.6 22 21.5 22.322.2 22.6 22.5 Polymers DER 331 Dow Chemical 22.5 23 23.6 22 21.5 22.322.2 22.6 22.5 Curatives Dicyandiamide DICY CGNA Air Products — — — — —— — — 3.7 DICY CG 325 Air Products 3.7 3.8 3.9 3.7 3.6 3.7 3.7 3.8 —Amine-Epoxy Adduct AJICURE PN-23 Ajinomoto 0.6 0.6 0.6 0.5 0.5 0.6 0.60.6 0.6 Blowing Agent CELOGEN AZ-120 Uniroyal 1.3 1.3 1.4 1.3 1.2 1.31.3 1.3 1.3 Diazacarbonamide Fillers Silica CAB-OSIL TS-720 Cabot 1.31.3 1.4 1.3 1.2 1.9 2.3 0.9 1.3 Glass Microspheres B-38/VS 5500 3M 32.833.6 34.4 32 31.3 32.6 32.4 32.9 32.8 Glass Fiber   —   — 9.4 7.2 4.911.4 13.4 9.3 9.3 9.4 9.4 Toughening/Flexibilizing NIPOL 1312 Zeon 4.74.8 4.8 4.6 4.5 4.7 4.6 4.7 4.7 Agent Lap Shear, psi 215 204 166 212 266154 234 181 168 3 Point Bend, psi 31.6 28 28.4 33.7 72 43.4 36.8 38 34.6

TABLE 5 Ex. Ex. Ex. Ex. Ex. 29 30 31 32 33 Wt. Wt. Wt. Wt. Wt. ComponentIdentity Supplier % % % % % Epoxy PEP 6134 Peninsula 21.5 21.4 21.3 21.321.2 Resins Polymers DER 331 Dow 21.5 21.4 21.3 21.3 21.2 ChemicalAdditional DICY CG Air 3.6 3.6 3.6 3.5 3.5 Curative 325 Products FillersSilica CAB-O- Cabot 1.2 1.5 1.8 2.2 2.6 SIL TS-720 Glass B-38/VS 3M 31.331.2 31.1 31 30.9 Micropheres 5500 Glass Fiber  —  — 13.4 13.4 13.3 13.313.2 Blowing BIK OT Uniroyal 0.4 0.4 0.4 0.3 0.3 Agent ActivatorToughening/ NIPOL Zeon 4.5 4.5 4.4 4.4 4.4 Flexibilizing Agent 1312 LapShear, 120 150 163 140 100 psi 3 Point 40 38 55.4 26 20 Bend, psi

TABLE 6 Ex. 34 Ex. 35 Ex. 36 Ex. 37 Ex. 38* Component Identity SupplierWt. % Wt. % Wt. % Wt. % Wt. % Epoxy Resins PEP 6134 Peninsula Polymers21.3 21.3 21.3 21.3 21.5 DER 331 Dow Chemical 21.3 21.3 21.3 21.3 21.5Curatives Dicyandiamide DICY CG 325 Air Products 3.6 3.6 3.5 3.5 3.6Amine-Epoxy Adduct AJICURE PN-23 Ajinomoto 0.5 0.5 0.5 0.5 1.8 BlowingAgent CELOGEN AZ120 Uniroyal 1.2 1.2 1.2 1.2 1.3 Blowing Agent BIK OTUniroyal 0.4 0.4 0.4 0.4 1.3 Accelerator Fillers Silica CABO-SIL TS-720Cabot 1.8 1.8 1.8 1.8 1.8 Glass Fiber   —   — 13.3 13.3 13.3 13.3 13.5Glass Micropheres B-38/V5 5500 3M 31.1 31.1 31.1 31.1 31.4Flexibilizing/Toughening NIPOL 1312 Zeon 4.4 4.4 4.4 4.4 4.5 AgentOrganometallates Titanates KEN-REACT KR-55 Kenrich Petrochemicals 0.40.4 0.4 0.4 — KEN-REACT 238M Kenrich Petrochemicals 0.2 0.2 0.2 0.2 —Zirconate KEN-REACT NZ-37 Kenrich Petrochemicals 0.2 0.2 0.4 0.4 — 3Point Bend, psi 29.2 40 30 40 32 *Comparative example

What is claimed is:
 1. A foamable composition comprising a) one or morethermosettable synthetic resins; b) one or more curatives; c) one ormore blowing agents; and d) one or more organometallate compoundsselected from the group consisting of organic titanates and organiczirconates in an amount effective to reduce corrosion of a metal surfacein contact with a foam produced from said foamable composition ascompared to a foam produced from an analogous foamable composition notcontaining any of said organometallate compounds.
 2. The foamablecomposition of claim 1 comprising at least one organic titanate and atleast one organic zirconate.
 3. The foamable composition of claim 1comprising at least one organic titanate which is an amine adduct of atetrasubstituted titanate.
 4. The foamable composition of claim 1comprising at least one organic titanate containing aphosphorus-containing substituent bonded to titanium.
 5. The foamablecomposition of claim 1 comprising at least one organic titanate ororganic zirconate containing at least one neoalkoxy substituent bondedto titanium or zirconium.
 6. The foamable composition of claim 1comprising at least one organic titanate which is a phosphite adduct ofa tetrasubstituted titanate.
 7. The foamable composition of claim 1comprising, a) at least one organic titanate selected from the groupconsisting of amine adducts of tetrasubstituted titanates and organictitanates containing at least one phosphato or pyrophosphato substituentbonded to titanium; b) at least one organic titanate different from theorganic titanate of (a) selected from the group consisting of organictitanates containing at least one neoalkoxy substituent bonded totitanium and phosphite adducts of tetrasubstituted titanates; and c) atleast one organic zirconate selected from the group consisting oforganic zirconates containing at least one neoalkoxy substituent bondedto zirconium and organic zirconates containing at least one benzoatesubstituent or derivative thereof bonded to zirconium.
 8. The foamablecomposition of claim 1 wherein at least one of the thermosettablesynthetic resins is an epoxy resin.
 9. The foamable composition of claim1 wherein at least one of the thermosettable synthetic resins is aglycidyl ether of a polyhydric phenol.
 10. The foamable composition ofclaim 1 wherein at least one of the blowing agents is a chemical blowingagent.
 11. The foamable composition of claim 1 wherein at least one ofthe curatives is a nitrogen-containing compound.
 12. The foamablecomposition of claim 1 additionally comprising hollow glassmicrospheres.
 13. The foamable composition of claim 1 additionallycomprising at least one additive selected from the group consisting offillers, flexibilizing/toughening agents, blowing agent activators,thixotropic/rheological control agents, colorants, silanes, andstabilizers.
 14. The foamable composition of claim 1 wherein theorganometallate compounds are present in an amount totalling from about0.1 weight % to about 2 weight % based on the overall weight of thefoamable composition.
 15. A foam obtained by heating and curing thefoamable composition of claim
 1. 16. A composite comprised of a solidarticle and the foam of claim
 15. 17. A foamable dough useful forproducing a structural reinforcement foam, said foamable doughcomprising a) from about 35 weight % to about 85 weight % of one or moreepoxy resins, wherein at least one of said epoxy resins is a glycidylether of a polyhydric phenol; b) from about 0.5 weight % to about 10weight % of one or more chemical blowing agents; c) from about 0.1weight % to about 15 weight % of one or more curatives, wherein at leastone of said curatives is a nitrogen-containing compound; d) one or morefillers, wherein from about 5 weight % to about 50 weight % of thefoamable dough is comprised of hollow glass microspheres; and e) fromabout 0.1 weight % to about 2 weight % total of at least two differentorganometallate compounds selected from the group consisting of: (i)amine adducts of tetrasubstituted titanates; (ii) organic titanatescontaining at least one phosphato or pyrophosphato substituent bonded totitanium; (iii) organic titanates containing at least one neoalkoxysubstituent bonded to titanium; (iv) phosphite adducts oftetrasubstituted titanates; (v) organic zirconates containing at leastone neoalkoxy substituent bonded to zirconium; and (vi) organiczirconates containing at least one benzoate substituent or derivativethereof bonded to zirconium, wherein said organometallate compounds arepresent in an amount effective to reduce corrosion of a metal surface incontact with the structural reinforcement foam produced from saidfoamable dough as compared to a foam produced from an analogous foamabledough not containing any of said organometallate compounds.
 18. Thefoamable dough of claim 17 comprising at least one organometallatecompound from group (i) or (ii), at least one organometallate compoundfrom group (iii) or (iv), and at least one organometallate compound fromgroup (v) or (vi).
 19. The foamable dough of claim 17 additionallycomprising glass fibers.
 20. The foamable dough of claim 17 wherein atleast one of the chemical blowing agents is selected from the groupconsisting of azodicarbonamide and sulfonyl hydrazides.
 21. The foamabledough of claim 17 wherein at least one of the curatives isdicyandiamide.
 22. The foamable dough of claim 17 wherein a urea ispresent as a blowing agent activator.
 23. The foamable dough of claim 17additionally comprising at least one additive selected from the groupconsisting of flexibilizing/toughening agents, colorants, silanes,stabilizers, and thixotropic/rheological control agents.
 24. Thefoamable dough of claim 17 wherein the polyhydric phenol is bisphenol A.25. The foamable dough of claim 17 wherein the epoxy resins containabout 2 epoxy groups per molecule and have epoxy equivalent weights offrom about 150 to about
 1000. 26. A structural reinforcement foamobtained by heating and curing the foamable dough of claim
 17. 27. Acomposite comprised of a ferrous article and the structuralreinforcement foam of claim 26.